A blend of Light Weight Material and Optimal Hull Design a good option to meet EEDI requirements?

In my earlier article I have conveyed my concept using Metal Matrix Nanocomposites in shipbuilding. As we know the EEDI is very well implemented and industry is actively looking for options, I am proposing this approach.

As we all know reducing structural weight is one of the most important ways of reducing fuel consumption and improving the performance of ships. 

My approach is to develop materials that combine relatively low mass (weight) with the requisite strength, flexibility, and other performance criteria like aluminum alloys. Less weight, consistent with other performance and safety requirements, means more useful work can be extracted from a unit of fuel or other energy source. Weight-reducing technologies are critical to the success of new, highly efficient energy technologies such as hybrid vehicles.

Shipbuilding is the second largest consumer of lightweight materials. There is a growing demand for the lightweight metal; Aluminum represents the second largest metals market in the world.  Light, strong, and corrosion-resistant aluminum is the ideal metal for shipbuilding.

As we know, an Aluminum property (Physical, chemical, mechanical) doesn’t match that required by shipbuilding industry, hence why don’t we reinforce the material using carbon nano tubes? Objectives of the reinforcement will be 

To increase the yield strength and tensile strength at room temperature and above while maintaining the minimum ductility or rather toughness.

1. Increase in fatigue strength, especially at higher temperatures
2. Improvement of thermal shock resistance,
3. Improvement of corrosion resistance,
4. Increase in Young’s modulus,
5. Reduction of thermal elongation.
6. Improve Resistance Stress corrosion cracking 

When it comes to design, According to study done by DTU (refer RINA Journals March and April 2012 for article “Back to Basics”). Industry is driven by Ship owners and economics and not the hydrodynamic knowledge. It should be noted that if hydrodynamics plays a major role. Hence fixing the designs gaps contributes to better performance of the ship which if coupled with light weight material should result in significant reduction in GHG gases, in other words meet EEDI requirements.

From the Material Point of View:

Most of the total ownership resides in operations, Maintenance and Sustainment:

Although the acquisition cost for the Al NC equivalent ship will be currently higher than that for the steel ship, the Al NC equivalent ship will have a lower total ownership cost.  This is because of fuel savings and lower maintenance needs.  The Aluminum ship does not require painting over its life, except for anti-fouling painting. It also has lower power machinery to repair, and less manning due to decreased onboard maintenance by the ship's crew a significantly higher residual value at end of life scrapping as well.  

Because the aluminum ship uses less fuel it will have a lower carbon footprint, than the steel vessel. 

Cost is counter balanced: The increased material and manufacturing costs for the proposed Al NC hull ship structure can be almost counterbalanced by taking advantage of the weight benefit of the Al NC in reducing either the draft or the block coefficient.  The reduced displacement reduces the required draft or block coefficient for the same principal dimensions and draft.  Less propulsion power is then required for the same speed and less fuel is required for the same endurance. Al NC ships can go faster speeds, carry bigger payloads and travel longer ranges while enjoying increased stability and better fuel efficiency. 

Fuel: As the weight is reduced so is the propulsion power required to drive the vessel. This increases the vessel’s endurance. That is for the same amount of fuel quantity an Aluminum ship can travel more distance than steel equivalent. There is a huge saving in fuel costs over the life time of the ship. 

Painting: No need to paint. Only anti fouling painting is only required in the underwater region of vessel. This in fact reduces an average of 8- 10 tons of weight for a ship of approximately 100 -150 m in Length. It also reduces the total cost. Assuming that the steel ship requires re-painting every five years a savings of $2 to $5 million per ship is possible over the life of the Al NC vessel.

Recycling: Theoretically Al is 100% recyclable. Aluminum has high residual value at end of life. Nearly 75% of the aluminum ever made is still in use today. When an Aluminum vessel reaches the end of its life span, it continues to provide tremendous value as a result of its high recycling value.

Crew: As the systems and machinery installed are smaller as compared to the steel ships, the maintenance required is less and so is the manning. Assuming this for a total life period of vessel this significantly contributes in reducing total ownerships.

Is industry ready to accept the new material in shipbuilding?

Leave your suggestions